DESCRIPTION OF NEW 



Unto venustus. Plate II. fig. 4. 



Testa elUplka, transversa, subcompressa, luted, incequilaterali ; valvulis suhtenuibus ; nati- 

 bus vix prominentibus ; dentibus cardinalibus parvis ; lateralibus subcurvis ; margaritd alba 

 et iridescente. 



Shell elliptical, transverse, somewhat compressed, yellowish, inequilateral ; valves 

 somewhat thick; beaks scarcely prominent ; cardinal teelh small ; lateral leeth rather 

 curved ; nacre pearly white and iridescent. 



Hab. Potosi, Missouri. John Perry, Esq. 

 Cincinnati, Ohio. T. G. Lea. 



My Cabinet. 

 Diam. -5, Length 1, Breadth 1-7 inches. 



Shell elliptical, transverse, somewhat compressed, yellowish, inequi- 

 lateral ; substance of the shell somewhat thick; beaks scarcely promi- 

 nent, pointed at tip, and furnished with very minute undulations; 

 ligament rather short ; epidermis yellow^, with green, somew'hat sinuous 

 rays; cardinal teeth small, elevated, deeply cleft in the left valve ; late- 

 ral teeth somewhat long, rather curved and enlarged at the posterior 

 end; anterior cicatrices distinct; posterior cicatrices confluent; dorsal 

 cicatrices placed in the centre of the cavity of the beaks; cavity of the 

 shell rather shallow; cavity of the beak small and angular; nacre thin 

 behind, pearly white and iridescent. 



Remarks. — The specimen here figured was sent to me some years 

 since by John Perry, Esq., who obtained it near the lead mines of Po- 

 tosi, in Missouri. Subsequently my brother, T. G. Lea, has found the 

 species near Cincinnati. As it very strongly resembles a young U. 

 crasstis (Say), it may very properly be placed in the group of which 

 that species may be considered the type. 



